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Old Jan 3, 2006, 5:37 PM   #1
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n.b. This isn't meant as a trade ad, just looking for advice from those more knowledgeable than me! Mods- please feel free to edit any or all of this post appropriately.

Hi,

I've started a company making and importing universal batteries. They are about the size of an Ipod, weigh around 150g and store 4000Mah charge, with a USB and 7.4V out.

What i was hoping someone could help me with is this:

Obviously the Digital camera market is a key market for me. I would like to be able to bundle with the batteries (or sell as add ons) connectors to charge digital cameras through their DC-in. These tend to be around 3v and can charge from the USB.

Does anyone know a good resource to find the different types of DC in cameras use?

I can already supply AA battery chargers that run from these bigger batteries, but i was hoping to be able to charge the cameras LI-ions directly? or atleast give people the opportunity to charge their lith-ions/polymers when away from a AC outlet.

Any other advice or help with any aspect of the batteries or the business would be much appreciated!

Thanks!

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Old Jan 3, 2006, 6:49 PM   #2
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I don't know of an easy way to see what the DC input specs are for a given model (for those that have a DC input), other than to look at it's specifications.

The camera manufacturers are probably as good of a resouce as any, since you can often find this information in published specifications (and many have downloadable manuals, too).

You may also want to take a look at some of the existing battery packs on the market. You can get them in different voltage levels, with a variety of different plug types designed to fit different cameras (including some designed to provide voltage step down functions). Here is an example compatibility chart for some of the Maha Powerbank battery packs:

http://www.thomas-distributing.com/m...bank-chart.htm

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Old Jan 3, 2006, 7:25 PM   #3
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Hi,

Thanks for the link.

Could someone give me a better understanding of voltage step-down? The products i have, according to the manufacturers, are 'universal' and i have charged many different types of cell phones (usually rated at 3.6V) from the USB out port, without what seems to be a problem.

Also, for some makes, I have been advised to put the battery output to 9.8V - to charge a 3.6V battery (this was advised for Nokia phones)

With this in mind, how important is a step-down converter?

Thanks.
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Old Jan 3, 2006, 8:05 PM   #4
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Different cameras have different input voltages. Most are at around 6 volts. But, some are 7.2 volts and some may be 5 volts. You'd need to check them out on a case by case basis.

Digital Cameras that have the ability to take a DC input do not normally use the USB connection for it. A separate port is provided.

The step down cables being provided by some battery pack manufacturers are designed to supply the correct voltage, as well as provide plugs that match up to the camera's input socket.

For example, if a camera needs a 5 volt input, and the battery pack is supplying 6 volts, you'd want a way to step down the voltage to 5 volts before it gets to the camera. Some of the cables provided by 3rd party battery pack providers perform this step down function (via electronics in the plug).

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Old Jan 3, 2006, 8:32 PM   #5
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hi,

What i meant to ask wasthat if one can charge a cell phone that is supposedly rated at 3.6V from a 5V USB, without, to the best of my (admitedly lacking) knowledge, any harm to the cellphone, then why does one need to step down voltages for cameras: is this a neccessity? If it is, then why is it possible to charge different cell phones at different voltages from the same USB plug.

Also- why aren't Cameras charged from USB? 5V is the right voltage to charge a large number of Cameras.. so i believe?

The more I learn, the less I understand...
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Old Jan 3, 2006, 9:17 PM   #6
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I don't know why they don't use the USB port. My guess is that the ports are just not rated for a high enough capacity.

I've seen some specs showing that "low current" devices should not exceed 100ma, and "high current" devices should not exceed 500ma. I don't know how the USB bus is supposed to distinquish between the two device types and how the current limits are determined.

Also, use of USB hubs may not allow for adequate power.

As for voltage differences between cameras, I don't know the answer to that one either. It would depend on the design of the camera's electronics.

Just because a camera uses a given battery voltage, doesn't mean that the electronics are designed to run off of that voltage.

The camera may have voltage converters/regulators built into it (for example, stepping up from 3.7 volts to 6 volts if that's what the camera's electronics need to work).

Most are probably designed to work between 5 and 6 volts (since many cameras used 4AA batteries initially). 4 AA Alkaline batteries would provide approximately 6 volts (4 x 1.5 volts = 6 volts), or 4 AA NiMH batteries would provide approximately 5 volts (4 x 1.2 volts = 5 volts).

But, you can't always go by that. Some models need higher voltages via their DC input (even though they are designed to run on 4 AA batteries).

For example, when testing one external power pack, Dave Etchells over at Imaging Resource found that some camera models needed over 8 volts to function properly (even though their DC input was marked as 6.5 volts).

http://www.imaging-resource.com/ACCS...00/DPS9000.HTM

I suspect that some cameras are probably designed for lower input voltages now, too (since many can run on 3.7 Volt Lithium Ion batteries now). But, again, you'd need to check them on a case by case basis to see if their DC input voltage is the same (for those models that have a DC input port).


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Old Jan 3, 2006, 9:25 PM   #7
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Thanks for the explanation.

I guess more testing is needed.



Any other ideas on what Digital camera users would want from a portable battery... apart from have the right voltage for their cam of course;-)


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Old Jan 3, 2006, 9:38 PM   #8
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I've got a portable battery pack (belt worn) that I've used with some older cameras.

But, the older cameras tended to draw a lot more current, and so you were somewhat limited by internal batteries (and AA capacities have climbed significantly over the past few years, too -- reducing the need for external battery packs even more).

Anymore, current draw is becoming so low, that it's not uncommon for users to get 400 shots from a single charge with some newer camera models.

So, external battery packs are probably not a high demand item anymore, especially given the low prices of generic Lithium Ion replacement batteries (and most newer models are switching from AA to Lithium Ion).

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